The invention is directed to a system for controlling the paper feed in printing mechanisms and the like, wherein the paper web to be transported is provided with perforations adapted to receive drive pins of feeding means therefor.
In printing mechanisms, particularly high speed printers, feeding systems are employed to control the movement of the paper advance through the printing station. Such feed systems may employ feed belts or feed wheels provided with suitable transport pins which are adapted to be received in the perforations in the paper web to be transported and thereby advance such paper web.
Paper feed mechanisms of this type are subject to breakdowns in the paper advancing operation, for example as a result of ripped perforations, tearing of the paper web, jamming of the paper, and lateral derailment of the paper web at the feed mechanism. In order to efficiently shutdown the printing apparatus, in the event of such a breakdown, the failure of the paper to advance must be discovered as quickly as possible following its occurrence, in order to correspondingly stop the printing mechanism.
To endeavor to accomplish the desired results and keep the data loss occurring in such situations to within narrow limits, monitoring systems have been devised. Prior systems of this type have employed a so-called cover-closing contact. In this type of construction, each feed system for the paper web is urged against the feed belt or wheel by a hinged cover which maintains the cover-closing contact in one position indicating that proper paper advance is taking place. If a breakdown should occur in the paper advance a jamming of paper will occur which moves or tips the cover and thereby opens the cover-closing contact, actuation of which thereby indicates that a breakdown has occurred in the paper advance movement.
This type of monitoring of the paper advance has the disadvantage that, before detection of the breakdown can take place, a paper jam must first form in the paper feed system. Consequently, the invention is directed to a monitoring system for the paper feed in which a breakdown of the paper feed advance movement is immediately detected.